The main elements of the type of bridge to which the invention is directed are: (a) a substructure; and (b) a superstructure.
A substructure is comprised of (1) foundations and (2) piers. The foundations are the components of the substructure that engage or interact with the earth to support the bridge structure. A foundation can be constructed of one or more piles, one or more concrete drilled shafts, one or more concrete mats, and combinations thereof. Presently, piles include precast concrete piles and steel piles. The piers are the components of the substructure that transfer the bridge structural loads to the foundations. A pier can be constructed of columns, struts, pile caps, pier caps, and combinations thereof. Presently, columns include cast in place columns, precast concrete columns, and steel columns.
A superstructure carries the traffic load (vehicular, rail, and/or pedestrian) on the bridge. A superstructure can be constructed using girders that each typically span the distance between two adjacent piers. Presently, girders include precast concrete girders, cast in place girders, precast concrete box girders, segmental box girders, steel girders, and steel box girders. Some superstructures use two or more different types of girders.
Presently, there are several methods of constructing a bridge comprised of a substructure and a superstructure (hereinafter referred to as a “bridge”) in situations in which there is limited access from the ground. Characteristic of each method is the use of one or more conventional cranes that are each capable of rotating a boom about horizontal and vertical axes to either move an element of bridge into place or manipulate a tool that is used in constructing the bridge. One method employs a crane that is positioned on top of and near the end of the existing superstructure to position a pile driver and a pile beyond the end of the superstructure so that the pile can be driven into the earth to form the next foundation. Typically, a second crane is used to provide piles to the pile driver associated with the first crane, construct the pier that engages the pile or piles of the foundation established by the first crane, and construct the, either alone or in combination with the first crane, the superstructure. A drawback associated with this method is that the piers must be spaced relatively close together due to the construction loads imposed upon the bridge by the crane, the pile driver, and the pile.
Another method for constructing a bridge when the bridge is being built over a watercourse or wetland involves using a temporary structure that extends outside the footprint of the resulting bridge to support cranes and the like that are used in constructing the bridge and, in particular, the substructure of the bridge. In many case, the temporary support structure adversely affects the portions of the watercourse or wetland that are outside the footprint of the bridge. Typically, the temporary support structure supports a first crane to which a pile driver has been attached, a second crane for loading a pile into the pile driver associated with the first crane, a third crane for constructing a pier on each of the foundations established by the first and second cranes, and a fourth crane for putting the girders in place between adjacent piers. In some cases, the third and/or fourth crane are replaced with a moveable gantry or truss that spans the distance between at least two adjacent piers and is located above and substantially parallel to the superstructure to construct the piers and establish girders between adjacent piers.
Also associated with the construction of bridges is the attachment of L-shaped form to the outer-most lateral girders and the subsequent pouring of concrete into the forms to establish an L-shaped concrete member along the lateral edges of the superstructure. These L-shaped members typically facilitate the establishment of barriers along the lateral edges of the superstructure and serve to contain the concrete or other fluid material that is used to establish the superstructure deck.